Layouts directory in SharePoint 2007

I have MOSS 2007. I can't find any _layouts directory.

Do I have to create it or do some configuration?

I need it because I have to add a JavaScript (.js) file to it according to this link: http://weblogs.asp.net/wesleybakker/archive/2009/03/05/select-multiple-list-items-in-sharepoint-feature.aspx

Edit:

For me - C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12 directory has only one fold开发者_C百科er called bin. There is no layouts directory. Where is it?

THe _layouts folder is the LAYOUTS folder in the C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\TEMPLATE folder.

C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\12\Layouts

The underscore is only used in urls.

Note that adding files to the system directly (without creating a solution package) is generally not a good idea.